共查询到20条相似文献,搜索用时 31 毫秒
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Park Yu-Hyeon Kim Hyung Jeek Son Ju Won Yoo Chan Min Khim Boo-Keun 《Ocean Science Journal》2019,54(3):487-495
Ocean Science Journal - This study evaluates the application of biomarkerbased temperature proxy data (alkenone with its resultant $$U_{37}^{K'}$$ index and glycerol dialkyl glycerol tetraether... 相似文献
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The Practical Salinity Scale (PSS) 1978 is defined only for salinities within the range 2-42. We have investigated the relationship between mass-determined salinity, electrical conductivity, and temperature for salinities between 0 and 2 with the aim of developing an extension to the Practical Salinity Scale 1978. The paper presents our data, on the basis of which the following correction is proposed to extend the validity of the equations defining the scale to the entire 0-42 range:S=summin{i=0}max{5} (a_{i}+b_{i}f(t))R_{t}^{i/2}-frac{a_{0}}{1 + 1.5x + x^{2}}-frac{b_{0}f(t)}{1+y^{1/2} + y + y^{3/2}} wheref(t)=frac{(t-15)}{1 + k(t-15) x=400R_{t} y=100R_{t} and the constanta_{i}, b_{i} , andk are defind by the Practical Salinity Scale 1978. 相似文献
4.
The ratiosR_{s,t,o} of electrical conductivity of seawater samples of precisely known salinity to standard seawater at the same temperature have been measured over a wide range of salinities from 0 to42permil S and over the full range of oceanic temperatures from -2 to35deg C. The samples withS<35permil were prepared by accurate weight dilution of standard seawater with distilled water. High salinity samples were prepared by fast evaporation of standard seawater and subsequent weight dilution into the already determined <35permil range. An equation was derived which expresses the S versusR_{s,t,o} relationship very precisely from1-42permil and at all temperatures, i.e.,S = f_{1}(R_{s,t,o}) + f_{2}(R_{s, t,o},t) =Sigma_{n=0}^{5} a_{n}R^{n/2}+ frac{Delta t}{1+kDelta t} Sigma_{n=0}^{5} b_{n}R^{n/2} whereDelta t = t-15deg C,R = R_{s, t.o} ; only the first termf_{1} is required at15deg C. The effeet of temperature on the electrical conductivity of standard seawater was also measured. The ratior_{t} of the conductivity at temperaturet to the conductivity at15deg C (C_{35,t, o}/C_{35,15,o} ) is very aeenrately expressed by a fourth degree equation int . i.e,r_{t}=Sigma_{n=0}^{4} c_{n}t^{n} These two equations are sufficient for all salinity determinations at normal atmospheric pressure. 相似文献
5.
If knowledge of our theories on the directivity of tsunamis had received worldwide attention, the following operations could have been carried out internationally just after the large earthquake of 19 September 1985 which occurred near Acapulco, Mexico. Having found the great circle, “line S” which is perpendicular to the coast around Acapulco, we could have calculated the angles between line S and line A and between line S and line D, where line A and line D are the great circle connecting Acapulco and Auckland, New Zealand and that connecting Acapulco and Duke of York Island (Chile), respectively. The resultant angles are 30?43′ and 41?49′(>68?48′/2), we could thereafter neglect the eastern half of the offshore energy flux. When we assume that the speed of trans-Pacific tsunami is 400 knots, the probability that the actual tsunami will come earlier than the calculated arrival time proves to be $$\frac{1}{{\sqrt {2\pi } }}\int_{ - {\text{ }}\infty }^{ - {\text{ }}0.689} {e^{ - t^{{2 \mathord{\left/ {\vphantom {2 2}} \right. \kern-\nulldelimiterspace} 2}} } dt = 0.2454} $$ Contact with New Zealand prior to the forecasted arrival time was essential, but the tsunami attention for the Japanese coast was unnecessary. Without such application of our directivity theories, frequent fruitless warnings will be issued for future trans-Pacific tsunamis. Quick improvements in warning procedures are required. 相似文献
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《Oceanic Engineering, IEEE Journal of》2009,34(4):407-422
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Systems of identical precisely spaced bubbles or similar monopole scatterers in water-e.g., inflated balloons or thin-walled shells-insonified at frequenciesomega_{SR} dose to their fundamental radial resonanceomega_{0} (bubble) frequency may themselves display resonance modes or superresonances (SR's) [1]. Ordinary single-bubble resonances magnify the local free-field pressure amplitudep_{1} by a factor(ka)^{-1} ,a being the radius andk the wavenumber in water: for air bubbles or balloons in water, this factor is of the order of 70. Under SR conditions each member of the system amplifies the local free-field amplitude by a further factor of order(ka)^{-1} . Depending upon geometry and other constraints, the pressure fieldP_{SR} on the surface and in the interior of each scatterer will then be in the range of10^{3}p_{1} to5 times 10^{3} p_{1} . This paper investigates the sensitivity of this phenomenon to small departures from the ideal model. In particular, it examines the effect of small differences in scatter positioning and volumes in the context of an SR system consisting of two bubbles/balloons close to the boundary of a thin elastic plate overlying a fluid half-space. It is found that, to observe the SR phenomenon, radii and positions should be controlled to within approximately 1/2 percent.P_{SR} is also sensitive to the angle of incidence of the plane wave train. For the simple system examined here, this sensitivity is considerable for either flexural wave trains or volume acoustic waves incident upon the bubble/ balloon pair (doublet). Practical uses of the phenomenon may range from the design of passive high-Q acoustical filter/amplifiers and acoustical lenses to improved source efficiencies. 相似文献
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Forty-three open-ocean observations of drag coefficients observed at Argus Island Tower near Bermuda by the dissipation technique resulted in constant drag coefficients for mean horizontal wind velocities between 7.8 and10.4 m .s^{1} in good agreement with the larger near-neutral data set of DeLeonibus and Simpson [1] and the neutral data of Large and Pond [2], both of whom observed10^{3}C_{10} = 1.2 whereC_{10} is the drag coefficient at l0 m. Ratios of vertical-to-horizontal wind velocity spectral densities averaged over an inertial subrange of 0.8 to 1.6 Hz ranged from 0.7 to 1.07 in agreement with the Busch and Panofsky [3] result that isotropy is approached only when the observation height is much greater than the Nyquist wavelength. 相似文献
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Motoaki Kishino Takashi Ishimaru Ken Furuya Tomohiko Oishi Kiyoshi Kawasaki 《Journal of Oceanography》1998,54(5):431-436
In-water algorithms for OCTS standard products were developed using in situ data and installed for operationally processing
at NASDA/EOC. This paper describes the in-water algorithms Version 1.0 for chlorophylla concentration, pigment concentration, and attenuation coefficient at a wavelength of 490 nm. The selected OCTS standard algorithms
(Ver. 1.0) are as follows:
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10.
Hasrizal Bin Shaari Masanobu Yamamoto Tomohisa Irino Tadamichi Oba 《Journal of Oceanography》2014,70(1):25-34
Isoprenoid glycerol dialkyl glycerol tetraethers (GDGTs) and alkenones were analyzed in sediment samples retrieved from Ocean Drilling Program Site 1241 covering the last 150000 years to understand the hydrological evolution of the eastern Pacific warm pool (EPWP). GDGT and alkenone concentrations showed higher values in marine isotope stage (MIS)-2 and MIS-6, which suggests the enhancement of primary production at glacial maxima. $ {\text{TEX}}_{86}^{\text{H}} $ - and $ U_{ 3 7^\prime }^{\text{K}} $ -derived temperature depicted different temperature evolutions. $ U_{ 3 7^\prime }^{\text{K}} $ -derived temperature was marked by small variation during the glacial–interglacial cycles, whereas $ {\text{TEX}}_{86}^{\text{H}} $ -derived temperature showed pronounced glacial–interglacial variation that was similar to Mg/Ca-derived temperature records from nearby cores in the EPWP. Given that enhanced primary production during glacial maxima suggests nutricline shoaling, unchanged $ U_{ 3 7^\prime }^{\text{K}} $ over glacial–interglacial cycles can be interpreted as the shift of alkenone production depth. $ {\text{TEX}}_{86}^{\text{H}} $ seems not to be influenced by glacial–interglacial changes in nutricline depths, recording an integrated temperature in surface and thermocline water. The shallow nutricline in the EPWP during glacial maxima most likely reflected the intense formation of Antarctic intermediate water. 相似文献
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Muryshev K. E. Eliseev A. V. Denisov S. N. Mokhov I. I. Arzhanov M. M. Timazhev A. V. 《Izvestiya Atmospheric and Oceanic Physics》2019,55(3):235-241
Izvestiya, Atmospheric and Oceanic Physics - The phase shift between changes in the global surface temperature Tg and atmospheric CO2 content $${{q}_{{{\text{C}}{{{\text{O}}}_{2}}}}}$$ has been... 相似文献
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Zhi Yang Jianfang Chen Min Chen Lihua Ran Hongliang Li Peng Lin Yong Zhu Chunsheng Wang Zhongqiang Ji Jingjing Zhang 《Journal of Oceanography》2018,74(1):101-113
To elucidate the sources and transformations of nitrogen in the South China Sea (SCS), the nitrogen isotopic composition of nitrate (\({\updelta }^{ 1 5} {\text{N}}_{{{\text{NO}}_{ 3} }}\)) was measured in seawater samples from the water column of this marginal sea and the adjacent western North Pacific Ocean (WNP). Comparison of the isotopic signatures from these two locations suggests that the main source of nitrogen into the SCS was nitrate that entered from the WNP through the Luzon Strait. Values of \({\updelta }^{ 1 5} {\text{N}}_{{{\text{NO}}_{ 3} }}\) were generally lower in the SCS than in the WNP, and the \({\updelta }^{ 1 5} {\text{N}}_{{{\text{NO}}_{ 3} }}\) maximum observed in the SCS intermediate water was lower than the corresponding WNP maximum. This pattern is attributed to mixing within the SCS in combination with the outflow of SCS intermediate water to the WNP. A mass balance model indicates that atmospherically derived N (a combined input of new nitrogen from marine N2 fixation and atmospheric deposition) supplied approximately 6% of the particulate nitrogen exported from the euphotic zone to the deep SCS. This supply of isotopically light nitrogen cannot, however, explain the low and downward-decreasing δ15N that has been previously observed in sinking particles of the deep SCS. We propose that an alternative explanation might be a downward-increasing ratio of isotopically light NH4 +-N to organic N due to the degradation of organic N within the sinking particles (i.e., relative enrichment of the NH4 +) and also particle incorporation of excreted ammonium from zooplankton. 相似文献
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Mouctar Kamara Rashila Deshar Sahadev Sharma Md. Kamruzzaman Akio Hagihara 《Journal of Oceanography》2012,68(6):851-856
Weller??s allometric model assumes that the allometric relationships of mean area occupied by a tree $ \bar{s} $ , i.e., the reciprocal of population density $ \rho $ , $ \bar{s}\left( { = {1 \mathord{\left/ {\vphantom {1 {\rho = g_{\varphi } \cdot \bar{w}^{\varphi } }}} \right. \kern-0em} {\rho = g_{\varphi } \cdot \bar{w}^{\varphi } }}} \right) $ , mean tree height $ \bar{H}\left( { = g_{\theta } \cdot \bar{w}^{\theta } } \right) $ , and mean aboveground mass density $ \bar{d}\left( { = g_{\delta } \cdot \bar{w}^{\delta } } \right) $ to mean aboveground mass $ \bar{w} $ hold. Using the model, the self-thinning line $ \left( {\bar{w} = K \cdot \rho^{ - \alpha } } \right) $ of overcrowded Kandelia obovata stands in Okinawa, Japan, was studied over 8?years. Mean tree height increased with increasing $ \bar{w} $ . The values of the allometric constant $ \theta $ and the multiplying factor $ g_{\theta } $ are 0.3857 and 2.157?m?kg???, respectively. The allometric constant $ \delta $ and the multiplying factor $ g_{\delta } $ are ?0.01673 and 2.685?m?3?kg1???, respectively. The $ \delta $ value was not significantly different from zero, showing that $ \bar{d} $ remains constant regardless of any increase in $ \bar{w} $ . The average of $ \bar{d} $ , i.e., biomass density $ \left( {{{\bar{w} \cdot \rho } \mathord{\left/ {\vphantom {{\bar{w} \cdot \rho } {\bar{H}}}} \right. \kern-0em} {\bar{H}}}} \right) $ , was 2.641?±?0.022?kg?m?3, which was considerably higher than 1.3?C1.5?kg?m?3 of most terrestrial forests. The self-thinning exponent $ \alpha \left( { = {1 \mathord{\left/ {\vphantom {1 {\varphi = }}} \right. \kern-0em} {\varphi = }}{1 \mathord{\left/ {\vphantom {1 {\left\{ {1 - \left( {\theta + \delta } \right)} \right\}}}} \right. \kern-0em} {\left\{ {1 - \left( {\theta + \delta } \right)} \right\}}}} \right) $ and the multiplying factor $ K\left( { = \left( {g_{\theta } \cdot g_{\delta } } \right)^{\alpha } } \right) $ were estimated to be 1.585 and 16.18?kg?m?2??, respectively. The estimators $ \theta $ and $ \delta $ are dependent on each other. Therefore, the observed value of $ \theta + \delta $ cannot be used for the test of the hypothesis that the expectation of the estimator $ \theta + \delta $ equals 1/3, i.e., $ \alpha = {3 \mathord{\left/ {\vphantom {3 2}} \right. \kern-0em} 2} $ , or 1/4, i.e., $ \alpha = {4 \mathord{\left/ {\vphantom {4 3}} \right. \kern-0em} 3} $ . The $ \varphi $ value was 0.6310, which is the same as the reciprocal of the self-thinning exponent of 1.585, and was not significantly different from 2/3 (t?=?1.860, df?=?191, p?=?0.06429), i.e., $ \alpha = {3 \mathord{\left/ {\vphantom {3 2}} \right. \kern-0em} 2} $ . Thus the self-thinning exponent is not significantly different from 3/2 based on the simple geometric model. On the other hand, the self-thinning exponent was significantly different from 3/4 (t?=?6.213, df?=?191, p?=?3.182?×?10?9), i.e., $ \alpha = {4 \mathord{\left/ {\vphantom {4 3}} \right. \kern-0em} 3} $ . Therefore, the self-thinning exponent is significantly different from 4/3 based on the metabolic model. 相似文献
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Yoshihiro Mazda 《Journal of Oceanography》1984,40(1):19-28
The process of material transport through a strait due to tidal flow is modeled, and then the differences between various concepts of tidal exchange which have been used hitherto are pointed out using this model. In particular, the exchange of water itself and the exchange of material should be distinguished even in the case where the material of interest is carried by the water,i.e., the material and water move as one body. Further, the physical meaning of “tidal trapping” (Fischeret al., 1979) is discussed by using the model in this paper. The relationship between the exchange ratio for the water itself (r) and the phase lag (δ) of material concentration to the tidal stream in a section of the strait, which is an important factor in tidal trapping, is obtained as follows: $$\delta = \tan ^{ - 1} \left( {\tfrac{1}{r} - 1} \right)$$ Observational results at Lake Hamana (Shizuoka Pref) and at Kabira Cove (Okinawa Pref.) support the validity of the above relationship. 相似文献
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Masanori Ito Yutaka W. Watanabe Masahito Shigemitsu Shinichi S. Tanaka Jun Nishioka 《Journal of Oceanography》2014,70(5):415-424
To estimate benthic denitrification in a marginal sea, we assessed the usefulness of \({\text{N}}_{2}^{*}\) , a new tracer to measure the excess nitrogen gas (N2) using dissolved N2 and argon (Ar) with N* in the intermediate layer (26.6–27.4σ θ ) of the Okhotsk Sea. The examined parameters capable of affecting \({\text{N}}_{2}^{*}\) are denitrification, air injection and rapid cooling. We investigated the relative proportions of these effects on \({\text{N}}_{2}^{*}\) using multiple linear regression analysis. The best model included two examined parameters of denitrification and air injection based on the Akaike information criterion as a measure of the model fit to data. More than 80 % of \({\text{N}}_{2}^{*}\) was derived from the denitrification, followed by air injection. Denitrification over the Okhotsk Sea shelf region was estimated to be 5.6 ± 2.4 μmol kg?1. The distribution of \({\text{N}}_{2}^{*}\) was correlated with potential temperature (θ) between 26.6 and 27.4σ θ (r = ?0.55). Therefore, we concluded that \({\text{N}}_{2}^{*}\) and N* can act complementarily as a quasi-conservative tracer of benthic denitrification in the Okhotsk Sea. Our findings suggest that \({\text{N}}_{2}^{*}\) in combination with N* is a useful chemical tracer to estimate benthic denitrification in a marginal sea. 相似文献
16.
Rationale for the measurement of open-ocean tsunami signatures are presented, and available pertinent data are reviewed. Models for tsunami signature and background noise are proposed in order to synthesize an optimum tsunami receiver. Using these models, the minimum tsunami amplitude (in cm) to yield the probability of correct tsunami detectionP_{D} = 0.999 and probability of false alarmP_{F} = 10^{-3} is found to be0.718/sqrt{f_{0}} , wheref_{0} is the tsunami dominant frequency (in cycles/h). A realizable receiver is proposed and its performance is evaluated using actual tsunami signatures. It is demonstrated that the detection of a tsunami with an average amplitude as small as 0.7 cm is possible for theP_{D} andP_{F} as above. Simulation results using synthesized background noise are shown. Tidal effects on the receiver performance also are considered and are found negligible for a certain range of the receiver parameters, resulting in a considerable reduction of the signal processing required. 相似文献
17.
Experimental results from an array of moored current meters and an HF ocean surface radar support the idea that line broadening on the radar spectra is caused by the velocity distribution within the radar target cell. The experiment was done in the wake of a small island where the velocity variations were severe. An estimate is made of the line broadening which can be expected. In a turbulent flow with dissipation rate of the orderepsilon sim 10^{-10}m^{2}s^{-3} and target cell size 1 3000 m, the line broadening isDeltaf sim 10^{-3} Hz. This would be resolved with a radar time series ofsim 20 min and indicates that the HF ocean surface radar technique has potential in the observation of surface velocity distributions. 相似文献
18.
A formulation for the aerodynamic roughness length of air flow over wind waves $$z_0 = \gamma {\text{ }}u_* /\sigma p$$ which was proposed by Toba (1979) and Toba and Koga (1986) from dimensional considerations with some data analysis, is shown to correspond with a formulation for irregular solid surfaces $$(z_0 /h) = a(h/l)^{1 + \beta } $$ which resulted from work by Woodinget al. (1973) and Kustas and Brutsaert (1986);u * is the friction velocity,σ p the spectral peak frequency of wind waves,h the mean height of the solid obstacles,l the mean distance between their crests, andα,Β, andγ are constants. This correspondence is reached by the existence of a statistical 3/2-power law and an effective dispersion relationship for wind waves. Because both approaches of parameterizingz 0 were arrived at independently, they provide each other mutual reinforcement. 相似文献
19.
The design and ultimate performance of an extremely low-frequency (ELF) superconducting quantum interference device (SQUID) antenna that is mounted in a submarine-towed buoy depends critically on the motion spectrum of the buoy. Motion spectrum measurements from near dc to 100 Hz were conducted on a hydrodynamically stabilized buoy while being towed in the 650-m towing basin of the David Taylor Naval Ship Research and Development Center, Carderock, MD. The spectra show that the angular motion of the buoy can be held to4 times 10^{-6} rad/sqrt{Hz} or less within the ELF receiver bandwidth of 30-130 Hz, as long as properly streamlined fairings are used on the hydrofoil trailing edges in order to prevent oscillations from vortex shedding. Low-frequency oscillations of the buoy were3 times 10^{-3} rad/sqrt{Hz} or less for frequencies down to 0.025 Hz. This performance of the buoy is sufficient to permit it to serve as a towed platform for the NRL prototype SQUID receiver. 相似文献
20.
《Oceanic Engineering, IEEE Journal of》1982,7(2):75-82
A triaxial set of underwater receiving coils was developed and tested. The receiving system was used jointly with an underwater, calibrated, horizontal, electric dipole source in studies of extremely low-frequency electromagnetic propagation. This paper discusses the electromechanical design of the receiver and tethering system and addresses system sensitivity and noise levels. The receiving system was used successfully in a series of measurements, in spite of serious motion noise contamination. A stationary system sensitivity of5 times 10^{-4} gamma/sqrt{Hz} was achieved. 相似文献